90089-27-3Relevant academic research and scientific papers
Diastereo- and Enantioselective Synthesis of 1,2-trans-substituted Cycloalkanecarboxylates and Sulfones by Michael-Initiated Cyclisation via SAMP/RAMP Hydrazones
Enders, Dieter,Scherer, Hermann J.,Runsink, Jan
, p. 1929 - 1944 (2007/10/02)
An efficient and flexible synthesis of 1,2-trans-substituted cycloalkanecarboxylates and sulfones of high diastereo- and enantiomeric purity is described.The key step of the procedure is a Michael-initiated ring closure (MIRC) reaction employing the SAMP/RAMP hydrazone method.Depending on the chain length of the ω-bromo(iodo)enoates 2,3 and the type of ketone SAMP-hydrazone 1, 3-, 5-, 6- and 7-membered cycloalkanecarboxylates 4-7 or cyclopentanesulfones 24 bearing two or three stereogenic centers are formed with very high asymmetric induction.In the same manner, MIRC reactions with ω-(ethoxycarbonyl)enoate 26 give rise to 3-substituted cyclopentanone-2-carboxylates 27, but with lower overall chemical yields.The relative and absolute configurations are based on X-ray structure analysis, spectroscopic and mechanistic investigations. - Key Words: SAMP Hydrazones / RAMP Hydrazones / MIRC reactions / Cycloalkanecarboxyl acid esters / Sulfones
